Conventionally, films and screens are used in radiography in medicine and industry. However, developing and storing the film used in radiography is inefficient in terms of costs and time.
In order to overcome this problem, a digital image sensor is currently widely used. Such an image sensor may be classified into an indirect conversion type and a direct conversion type.
In the indirect conversion type, X-rays are converted into visible rays using a scintillator, and the visible rays are then converted into electrical signals. On the other hand, in the direct conversion type, the X-rays are directly converted into electrical signals using a photoconductive layer. Since a separate scintillator is not required and light does not spread in the direct conversion type, the direct conversion type is suitable for high-resolution systems.
The photoconductive layer used in the direct conversion type is formed on the surface of a CMOS substrate by deposition. However, the photoconductive layer adheres poorly to the protective film of the surface of the CMOS substrate. Therefore, the photoconductive layer may be peeled from the surface of the substrate.